Recently, there are many cases where a plurality of monitoring cameras are installed in various places, such as a large store (for example, a do-it-yourself store or a shopping mall), a public facility (for example, a station or a stadium), an office, a plant, and a warehouse, and the respective monitoring cameras photograph a monitoring target, such as a person, in a monitoring area of each of the monitoring cameras. In addition, in a case where a predetermined matter (or also referred to as an “event”), such as an accident, occurs in the monitoring area, a security system, which informs or reports a manager of a monitoring target place, a security contract company, a police officer, or the like using the types of monitoring cameras, has been used.
As an example of a security system according to the related art, as disclosed, for example, in PTL 1, a security system has been known which detects a suspicious person who intrudes into a monitoring area in the vicinity of a building, and gives an alarm. In a case where a first mobile body who is a permitted person to enter a monitoring area and a second mobile body who is a non-permitted person to enter the monitoring area are simultaneously detected in the monitoring area, the security system determines whether or not the non-permitted person is a suspicious person according to a moving locus of the permitted person and a moving locus of the non-permitted person. Therefore, the security system is capable of accurately detecting, for example, a housebreaker who tries to intrude into indoors by threatening a user.